The autobiography
is wonderful, and brilliant, but understand it is not so truthful. The type of aphorism you cited is typical of his output. It most likely never happened, but it should have happened. This is like Franklin's great public persona of temperance even though he was a notorious drunk.
Franklin was a scoundrel, an inveterate liar, skirt-chaser, always obese, and extremely lazy. A man of great intelligence, appetites, and very little in the way of self-restraint.
He would generally sleep till noon or later. He'd lie naked on his bed until the afternoon, opening the windows, and calling it an "air shower". He had many mistresses, a knack for self-promotion, and swindled several business partners.
At the same time, he was one of the most brilliant, wise, and influential men in the colonies, making important scientific discoveries, establishing hospitals, fire departments, post offices, libraries, schools, and many other projects. A successful author, inventor, diplomat, business man, and polymath, his work infused with wisdom, creativity, and common sense. He makes the modern "3 hour work week" sound like an amateur enterprise. It's incredibly how productive he was.
Well, at least he claimed the bulk of the credit for the public works -- his drinking buddy and dear friend Chief Justice William Allen also played a big role (until the relationship soured and Allen had him fired from trusteeship of the Academy of Philadelphia due to yet another financial dispute).
But Franklin was a great schmoozer, and he knew what needed to be done, how to get it done, and then how to take credit. He was extremely popular, told great stories, and was generally the smartest man in the room wherever he went.
But later in his life, when he discovered his own son was following down the same dissolute path, he wrote this autobiography as a hagiography to hard work and self-discipline, and had the big brass balls to portray himself as that early-to-bed, early-to-rise, temperate moral paragon, even though all of his contemporaries understood exactly what kind of a man he was, and must have laughed their asses off when reading that book.
And yet, it's a masterpiece. A critically important historical document while at the same time being enjoyable to read and inspiring millions. Franklin wins again.